Precombustion chamber



Patented Mar. 24, 1953 UNITED STATES PATENT PRECOMBU'STION Robert H. aLoughran, :East Hartford, Conn as.- .sisncr to Un ted A c f C rp ratio Ea t Hartford, Conn, a corporation of Delaware Application June 17, 1949, Serial No. 99,603

This invention relates to improvements in precombustion chambers as used in burners in gas turbine power plants.

One of the problems connected with gas turbine power plant burners is the use of the proper fuel in combination with the proper fuel nozzle pressure in order that ,the combustion of the charge within the burner .is as complete as possible. A feature of this invention is a precombustion chamber which over a wide range of fuels as .well as a wide range of fuel nozzle pressures is conducive to .ccmplete combustion (111.6 to the extended transit time of the fuel particles within the combustion zone.

A problem in connection with gas turbine power plants is to provide burneroperation which is insensitive to sudden changes of the rate of fuel and air flow. A feature of the invention is the localization of the critical primary combus/tion in and .adiacent to the p mbu ti chamber where flows are insensitive to sudden changes of total fuel and air flow. A feature of the invention is the localization of the major portion of combustion in and adjacent to the precombustion chamber to provide fuel-air ratios conducive to complete combustion when the total fuel-air ratio is relatively low.

The invention has particular application to aircraft gas turbine power plant burners. One of the problems in aircraft gas turbines is the excessive length of the burner necessary to support combustion due to the high velocity of the gases moving through the burner. A feature of this invention is a precombustion chamber which moves the nozzle end of the burner flame upstream toward the fuel nozzle and thus enables a reduction in the overall length of the burner.

Other objects and advantages will be more particularly pointed out or will become apparent as the description proceeds.

In the accompanying drawing, in which like reference numerals are used to designate similar parts throughout, there is illustrated what is considered to be a preferred embodiment of the invention.

In the drawing:

Fig. 1 is a longitudinal sectional View ofa gas turbine power plant burner unit showing the location and features of the precombustion chamber constructed according to this invention.

Fig. 2 is a sectional view of the precombustion chamber along line 22 of Fig. 1.

Fig. 3 is a longitudinal view of another type of precombustion chamber.

Fi 4 is an end iew of th me dmbustide chamber illustrated in Fissh wing th Peri at d and se on a viewed r m l ne 4-14.,

Re r n to th d awin in detail, the burner unit i indicated generally in Fi 1 at 1.9 id

burner .unit having inlet l2 where corn tign.

,Fuel noz l 24. i centr ll h ated bu ner in e '2 and d scharges f l a th ehtrance to the precombustion chamber. Conduit 26 supplies fuel to this nozzle from a source not shown. Retractable ignitor 28 is located within burner unit [0 and adjacent to precombustion chamber l6 for starting the combustion process of the fuel-air mixture within the chamber.

Combustion supporting means entering the inlet of the burner, from a compressor or some other source upstream of the burner, divide as they pass into the burner unit. Part of the gases are directed by conical shell 39 attached to conical shell I9 to precombustion chamber it, although a quantity is spilled out around support legs 18 into chamber 3| surrounding the precombustion chamber. The major portion of the gases entering the burner passes through annular chamber 32, of which conical shell l9 forms the inner wall, and are admitted to combustion chamber 34 through openings 36 at various stages along the length of the burner;

Gases passing over nozzle 24 pick up fuel and carry it into precombustion chamber it where the mixture is burned. The combustion which takes place within this chamber causes an increase in the specific volume of the gases with the result that the flow of flame'from the precombustion chamber into combustion chamber 34 takes place with extremely high velocity turbulence and is rapidly mixed with the remaining air entering combustion chamber 34 through openings 36.

A variation in the construction of the precombustion chamber is illustrated in Figs. 3 and 4. Chamber 38 is shown having perforations or holes 40 about its circumference which extend over the greater portion of its length. Cap 42 is provided over the downstream end of the precombustion chamber and this cap is provided with a series of holes 44 similar to those in member 38. Other variations in the arrangement and size of the perforations can be used with equal success.

Whilethere has been illustrated and described a particular mechanical embodimentof the idea of the invention, it is to be understood that the invention is not limited to the particular mechanical embodiment so illustrated and described, but that such changes may be resorted to as come within the scope of the appended claims.

I claim:

1. A burner unit comprising an outer casing, an inner casing, the inner casing defining a combustion chamber, a precombustion chamber mounted within the inner casingand at the inlet to the combustion chamber, the precombustion chamber being cylindrical inform and having a plurality of holes over the greater portion of its length, the downstream end of said precombustion chamher being closed by a cap having a plurality of holes thereinymeans for supplying combustion supporting gases to the burner unit, means for diverting a portion of the combustion supporting gases into the precombustion chamber, the precombustion chamber being spaced from the inner casing inlet so that a portion of the combustion supporting gases entering the precombustion chamber can enter the area surrounding the precombustion chamber, an annular passage between the inner and outer casings for the flow of combustion gases therethrough, the inner casing having openings through which combustion supporting gases in the annular passage can be admitted to the combustion chamber.

2. A burner unit comprising an outer casing, an inner casing, the inner casing defining a combustion chamber, a precombustion chamber mounted within the inner casing and at the inlet to the combustion chamber, the precombustion chamber being cylindrical in form and having a plurality of holes over the greater portion of its length, the downstream endof said precombustion chamber being closed by a cap having a plurality of holes therein, means for supplying combustion supporting gases to the burner unit, a conical shield for diverting a portion of the com bustion supporting gases into the precombustion chamber, the precombustion chamber being spaced from the inner casing inlet so that a portion of the combustion supporting gases entering the precombustion chamber can enter the area surrounding the precombustion chamber, an annular passage between the inner and outer casings for the fiow of combustion gases therethrough, the inner casing having openings through which combustion supporting gases in the annular passage can be admitted to the combustion chamber.

ROBERT H. LOUGI-IRAN.

REFERENCES CITED The following references are of record in the file of this patent: V

UNITED STATES PATENTS Number Name Date 2,438,858 Lindsey et al Mar. 30, 1948 2,445,466 Arnhym July 20, 1948 2,446,059 Peterson et a1 July 27, 1948 2,500,925 Bonvillian et a1. Mar. 21, 1950 V FOREIGN PATENTS Number Country 7 Date 879,123 France Nov. 10, 1942 

